.TH syscount 8  "2017-02-15" "USER COMMANDS"
.SH NAME
syscount \- Summarize syscall counts and latencies.
.SH SYNOPSIS
.B syscount [-h] [-p PID] [-i INTERVAL] [-d DURATION] [-T TOP] [-x] [-e ERRNO] [-L] [-m] [-P] [-l]
.SH DESCRIPTION
This tool traces syscall entry and exit tracepoints and summarizes either the
number of syscalls of each type, or the number of syscalls per process. It can
also collect latency (invocation time) for each syscall or each process.

Since this uses BPF, only the root user can use this tool.
.SH REQUIREMENTS
CONFIG_BPF and bcc. Linux 4.7+ is required to attach a BPF program to the
raw_syscalls:sys_{enter,exit} tracepoints, used by this tool.
.SH OPTIONS
.TP
\-h
Print usage message.
.TP
\-p PID
Trace only this process.
.TP
\-i INTERVAL
Print the summary at the specified interval (in seconds).
.TP
\-d DURATION
Total duration of trace (in seconds).
.TP
\-T TOP
Print only this many entries. Default: 10.
.TP
\-x
Trace only failed syscalls (i.e., the return value from the syscall was < 0).
.TP
\-e ERRNO
Trace only syscalls that failed with that error (e.g. -e EPERM or -e 1).
.TP
\-m
Display times in milliseconds. Default: microseconds.
.TP
\-P
Summarize by process and not by syscall.
.TP
\-l
List the syscalls recognized by the tool (hard-coded list). Syscalls beyond this
list will still be displayed, as "[unknown: nnn]" where nnn is the syscall
number.
.SH EXAMPLES
.TP
Summarize all syscalls by syscall:
#
.B syscount
.TP
Summarize all syscalls by process:
#
.B syscount \-P
.TP
Summarize only failed syscalls:
#
.B syscount \-x
.TP
Summarize only syscalls that failed with EPERM:
#
.B syscount \-e EPERM
.TP
Trace PID 181 only:
#
.B syscount \-p 181
.TP
Summarize syscalls counts and latencies:
#
.B syscount \-L
.SH FIELDS
.TP
PID
Process ID
.TP
COMM
Process name
.TP
SYSCALL
Syscall name, or "[unknown: nnn]" for syscalls that aren't recognized
.TP
COUNT
The number of events
.TP
TIME
The total elapsed time (in us or ms)
.SH OVERHEAD
For most applications, the overhead should be manageable if they perform 1000's
or even 10,000's of syscalls per second. For higher rates, the overhead may
become considerable. For example, tracing a loop of 4 million calls to geteuid(),
slows it down by 1.85x when tracing only syscall counts, and slows it down by
more than 5x when tracing syscall counts and latencies. However, this represents
a rate of >3.5 million syscalls per second, which should not be typical.
.SH SOURCE
This is from bcc.
.IP
https://github.com/iovisor/bcc
.PP
Also look in the bcc distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Sasha Goldshtein
.SH SEE ALSO
funccount(8), ucalls(8), argdist(8), trace(8), funclatency(8)
